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EDITED BY KRISTEN MUELLER AND JAKE YESTON

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20 JULY 2012 VOL 337 SCIENCE www.sciencemag.org

S O C I O L O G Y

Intimidated by Equations?

Although there is general agreement on the value of a strong tie between theory and data, forging links between theoretical and em-pirical approaches (and practitioners) is not as straightforward as it should be. New evidence of this disconnect comes from the work of Fawcett and Higginson, who examined the use of mathematical equations in 649 papers dealing with ecology and evolution that were published in 1998. They gathered citation data, exclud-ing instances of self-citation. An increase in the number of equations per page of main text cor-responded to a lower rate of citations. Overall, each additional equation in the main text of a paper was associated with a 28% decrease in the citation rate. Burying the equations in an appendix had a salutary effect on citation rate. When the citing papers were divided into theo-retical and nontheoretical on the basis of their use of the word “model” in the abstract or title, the authors observed that the negative effect was due to the nontheoretical papers not citing papers with equations. There are caveats to the conclusions—examinations over longer periods of time, analysis of the relative content of the papers, and examination of the effect for online rather than print publication are all warranted. Although the authors conclude that better math education for biologists is the best long-term solution, they suggest that more immediate strategies could include the addition of explana-tory text between equations. — BJ

Proc. Natl. Acad. Sci. U.S.A. 109, 10.1073/

pnas.1205259109 (2012).

E C O L O G Y

Half Truths

Deception is complicated because it requires the cognitive skills to both assess the potential for its effi cacy and to carry it off. Cepha-lopods are known masters of deceptive behavior, often using camoufl age as a way to rapidly mimic their environment, or even other organisms, in their attempts to avoid predation. Brown et

al. now show that mourning cuttlefi sh (Sepia

plangon) have taken this exceptional deceptive ability a step farther than mere run-of-the-mill camoufl age. In most cuttlefi sh species, courting males assume a particular coloration when at-

advantageous in many contexts and suggest that these types of social and deceptive interactions may have helped to shape the high cognitive functioning of cephalopods. — SNV

Biol. Lett. 8, 10.1098/rsbl.2012.0435 (2012).

C H E M I S T R Y

A Glimpse of Gold

Gold nanoparticles supported on titania have high catalytic activity; for example, in the oxida-tion of carbon monoxide at room temperature. What are the structural properties of the Au/TiO2 catalyst that enable this catalytic activity? Transmission electron microscopy has provided structural information, but the strong electron beam can damage the system, and it remains unclear whether the associated images represent the active structure of the catalyst. Kuwauchi

tempting to mate with females. This coloration attracts females but can also attract rival males, who may displace the courting male. In order to avoid attracting these potential competitors but

still maintain the female’s attention, males will often perform split coloration displays. They mimic female coloration on the side of their bodies facing a rival, while displaying male courtship coloration on the side facing the

female. Males perform this split display only when they are approached by a single male, presumably because it is only under these circumstances that they are able to maintain an appropriately deceptive angle. These results confi rm the idea that mimicry can be highly

One method for creating ordered mesoporous materials is to use the phase separation of

block copolymers to create a mold for patterning a second material. Typically, the structure

of the template is fi xed after solvent evaporation. Schuster et al. applied small-angle x-ray

scattering (SAXS) to follow the pyrolytic formation of mesoporous carbon fi lms using com-

mercial triblock polymers as templates and oligomeric resol as a carbon precursor. They

spin-coated these solutions onto silicon substrates or spread them onto the surface of porous

anodic alumina membranes, then monitored the thermal evolution of their structures with

grazing incidence or in situ SAXS, respectively. Analysis showed that the self-assembly of the

mesoporous phase (cylindrical holes in a face-centered orthorhombic or circular hexagonal

structure, respectively) does not occur after solvent evaporation but during pyrolysis, and

that changes in the heating rate can lead to changes in the unit-cell parameters. — PDS

J. Am. Chem. Soc. 134, 10.1021/ja208941s (2012).

MATERIALS SCIENCE

Hot Templating

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www.sciencemag.org SCIENCE VOL 337 20 JULY 2012

et al. now report the use of environmental

transmission electron microscopy, which al-

lows the catalyst to be studied under reaction

conditions. They fi nd that the nanoparticle

morphology varies systematically in differing

environments, changing from faceted to round,

depending on the gases present. In contrast, the

support maintains its crystallinity throughout

the experiments, and the interface between the

particles and the support also remains stable.

By systematically studying the effects of electron

irradiation on the structure, the authors derive

conditions under which no detectable structural

damage occurs, thus making it possible to de-

duce the intrinsic structure of the catalyst under

reaction conditions. — JFU

Angew. Chem. Int. Ed. 51, 10.1002/

anie.201201283 (2012).

P H Y S I C S

Intrinsic Origins

Interfacing two unlike materials may give rise

to unexpected properties resulting from the

asymmetry of the structure. Such is the case in

two-dimensional interfaces of perovskite oxide

fi lms; in the best-known example of the LaAlO3/

SrTiO3 (LAO/STO) interface, ferromagnetism has

been observed even though neither of the two

materials is magnetic in the bulk. This and other

interface effects are thought to originate from

STO, but whether they are an intrinsic property

of the electron liquid in STO is not known.

Moetakef et al. study the magnetism in STO

using two systems: GdTiO3/STO heterostructures

and La-doped STO fi lms; in both cases, STO is

doped with carriers, from the interface or the

La dopants, respectively. The authors observe

ferromagnetism in both systems, and super-

conductivity coexisting with magnetism in the

doped fi lms. The ferromagnetic Curie tempera-

ture increases strongly with the carrier density

measured through the Hall effect, and the data

from the two systems fall onto the same curve,

indicating universal dependence and an intrinsic

mechanism. — JS

Phys. Rev. X 2, 021014 (2012).

C H E M I S T R Y

Figure Nine

Nitrogen occurs naturally as a rather tightly

bound neutral dimer, and anionic azide (N3−)

salts have long been accessible as well. A cation

composed purely of nitrogen arrived only much

more recently on the scene, with the preparation

of an N5+ salt about a decade ago. The heavier

congener phosphorus has followed a similar

path: a variety of well-established neutral and

negatively charged morphologies, but until now

no tractable cation salts. Köchner et al. have

fi lled the gap with the preparation of a P9+ salt.

Key to its isolation was the use of an especially

inert, aluminum-centered counterion adorned

with trifl uoromethyl groups. The synthesis

entailed oxidation of neutral P4 by the nitroso-

nium salt of this counterion in dichlorometh-

ane solvent. Ultraviolet irradiation facilitated

reaction of an apparent [P4NO]+ intermediate

(and precipitation of excess neutral phosphorus)

without damaging the ultimate product, which

was isolable as a yellow-orange powder. Nuclear

magnetic resonance spectroscopy in conjunction

with theoretical calculations revealed a fi gure

8-type structure, of D2d symmetry, in which a

central tetracoordinate P atom bridges two clus-

ters of four P atoms each. The salt was also char-

acterized by mass spectrometry and infrared and

Raman spectroscopy, and persisted for weeks in

room-temperature solution. The authors envision

prospective applications of the salt in currentless

deposition protocols. — JSY

Angew. Chem. Int. Ed. 51, 6529 (2012).

E C O L O G Y

Diversity Persists

Marine ecosystems are characterized by high

tropical and low polar biodiversity, and are cor-

related with water temperature. Fossil evidence

hints at the persistence of such gradients for

over 270 million years, but little is known about

the details. Yasuhara et al. have chosen to exam-

ine the fossil record for North Atlantic

zooplankton, because the fossils are abundant

and the record is the most complete of any

marine taxon. Times slices spanning the past

3 million years showed that tropical-high and

polar-low diversity persisted throughout this

period, with highest diversities during the mid-

Pliocene. It seems that the species that have

gone extinct since the Pliocene had narrower

thermal tolerances than modern species and

were selected out by the glaciation. — CA

Ecol. Lett. 15, 10.1111/j.1461-

0248.2012.01828.x (2012).

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